[G4] Extra RAM slot in Digital Audio 733

[Eric Buczynski]

Hi all.  I have a G4 Digital Audio upgraded to 1.2 ghz, and RAM maxed  
out at 1.5 GB.  There's something that's been bugging me for a  
while.  I know that this Mac only has 3 RAM slots, yet when I go to  
the system profiler and check the memory heading, it shows a 4th  
memory slot as being empty.  DIMM slots J21, J22, and J24 show the  
512MB sticks, but then it shows DIMM3/J24 as being empty.  Is this a  
fluke at all or is there a way to tap into this?  I thank all who  
assist me on this and I apologize for asking if this question has  
been answered before recently.

Eric Buczynski